Dual track variable orifice mount

ABSTRACT

A powertrain mount comprises an orifice plate including two tracks, a control track and an isolation track. The control track is spirally formed within the orifice plate, which has an exit and entrance on either side of the plate. The control track provides damping to control damping from engine bounce; whereas, the isolation track controllably provides dynamic rate dip. The isolation track is formed between an alignment plate and rotatable track member, each having an exit and entrance, respectively. The rotatable track member and the alignment plate are sealingly engaged and affixed to a decoupler and an annular area disposed about the orifice plate of the powertrain mount. The exit of the alignment plate is adjacent the decoupler. The rotatable track member forms a cavity with the molded body of the powertrain mount, with the entrance exposed to fluid within the cavity for controlling and minimizing vibrations within the powertrain. The isolation track has a track length that may be varied by rotation of the track member and its entrance. Various magnitudes of disturbance frequencies may be managed and controlled by either the fixed control track and/or the variable isolation track within the powertrain mount.

TECHNICAL FIELD OF THE INVENTION

The present invention relates to powertrain mounts for motor vehicles,and more particularly to a powertrain mount having a controllablecompliant member.

BACKGROUND OF THE INVENTION

It is desirable to provide motor vehicles with improved operatingsmoothness by damping and/or isolating powertrain vibrations of thevehicle. A variety of mount assemblies are presently available toinhibit such engine and transmission vibrations. Hydraulic mountassemblies of this type typically include a reinforced, hollow rubberbody that is closed by a resilient diaphragm so as to form a cavity.This cavity is separated into two chambers by a plate. A first orprimary chamber is formed between the orifice plate and the body, and asecondary chamber is formed between the plate and the diaphragm.

The chambers may be in fluid communication through a relatively largecentral passage in the plate, and a decoupler may be positioned in thecentral passage of the plate disposed about the passage to reciprocatein response to the vibrations. The decoupler movement alone accommodatessmall volume changes in the two chambers. When, for example, thedecoupler moves in a direction toward the diaphragm, the volume of theportion of the decoupler cavity in the primary chamber increases and thevolume of the portion in the secondary chamber correspondinglydecreases, and vice-versa. In this way, for certain small vibratoryamplitudes and generally higher frequencies, fluid flow between thechambers is substantially avoided and undesirable hydraulic damping iseliminated. In effect, the decoupler is a passive tuning device.

As an alternative or in addition to the relatively large centralpassage, an orifice track is normally provided. The orifice track has arelatively small, restricted flow passage extending around the perimeterof the orifice plate. Each end of the track has an opening, with oneopening communicating with the primary chamber and the other with thesecondary chamber. The orifice track provides the hydraulic mountassembly with another passive tuning component, and when combined withthe decoupler, provides at least three distinct dynamic operating modes.The particular operating mode is primarily determined by the flow offluid between the two chambers.

More specifically, small amplitude vibrating input, such as fromrelatively smooth engine idling or the like, produces no damping due tothe action of the decoupler, as explained above. In contrast, largeamplitude vibrating inputs, such as large suspension inputs, producehigh velocity fluid flow through the orifice track, and an accordinglyhigh level of damping force and desirable control and smoothing action.A third or intermediate operational mode of the mount occurs duringmedium amplitude inputs experienced in normal driving and resulting inlower velocity fluid flow through the orifice track. In response to thedecoupler switching from movement in one direction to another in each ofthe modes, a limited amount of fluid can bypass the orifice track bymoving around the edges of the decoupler, smoothing the transition.

Prior decoupled powertrain mount designs therefore employ a decouplerthat is dependent of vibration amplitudes/frequencies duringcompressions of the mount during fluid flow through the orifice plate.In some vehicle states, such as high-speed shake, it is advantageous toprovide damping for small amplitude vibrations. During high-speed shakeconditions, small imbalances in the vehicle's wheels excite thepowertrain, which result in vibrations inside the cabin of the vehicle.By controlling the powertrain, providing damping, the vibrations insidethe cabin of the vehicle are reduced.

For small mount displacements the dynamic stiffness of the mount isapproximately the same as the static stiffness of the mount. Ideally,for isolation functions of a powertrain mount, the dynamic rate at thedisturbance frequency should be as low as possible. Therefore, it isalso desirable to lower the dynamic rate of the mount below a staticrate of the mount at engine disturbance frequencies.

Prior powertrain designs also incorporate the use of a single orificetrack to control both isolation and damping functions. Such designsrequire the powertrain mount to change between functions when someengine and environment conditions require both functions simultaneously.For example, a single-track orifice plate must change from bouncecontrol (at around 10 Hz) to isolation (which starts at approximately 20Hz).

It is desirable, therefore, to provide a powertrain mount that overcomesthese and other disadvantages.

SUMMARY OF THE INVENTION

The present invention is a powertrain mount comprising an orifice plateincluding two tracks, a control track and an isolation track. Thecontrol track includes a fixed spirally formed track within the orificeplate, which has an exit and entrance on either side of the plate. Theisolation track is formed between an alignment plate and rotatable trackmember, each having an exit and entrance respectively. The rotatablemember and the alignment plate are sealingly engaged and affixed to adecoupler and an annular area disposed about the orifice plate of thepowertrain mount. The exit of the alignment plate is adjacent thedecoupler. The rotatable member with the orifice plate forms a cavitywith a molded body of the powertrain mount, with the entrance of therotatable member exposed to fluid within the cavity for controlling andminimizing vibrations within the powertrain. The isolation track has atrack length that may be varied by rotation of the track member and itsentrance. Various magnitudes of disturbance frequencies may be managedand controlled by either the fixed control track and/or the variableisolation track within the powertrain mount.

Accordingly one aspect of the invention includes rotation of therotatable member and its entrance changes the length of the variabletrack. A motor operably connected and adapted to the rotatable member torotate the rotatable member based on vibration frequencies. Rotation ofthe rotatable member changes the length of the variable track and allowsfluid flow through the entrance of the rotatable member, along theisolation track, and to the decoupler via the exit of the alignmentplate.

Another aspect of the present invention is to provide a powertrain mountof the type described above that improves isolation and damping of themount at particular vibration disturbance frequencies. Still anotheraspect of the present invention is to provide a powertrain mount of thetype described above in which specific ranges of amplitude frequenciesof the powertrain are isolated or damped by selectively rotating therotatable member to engage the decoupler member within the isolationtrack, while the control track passively controls other discreetvibrations.

The foregoing and other features and advantages of the invention willbecome further apparent from the following detailed description of thepresently preferred embodiments, read in conjunction with theaccompanying drawings. The detailed description and drawings are merelyillustrative of the invention rather than limiting, the scope of theinvention being defined by the appended claims and equivalents thereof.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is an exploded perspective view of a powertrain mount accordingto the present invention for a motor vehicle;

FIG. 2 is a top perspective view of an orifice plate including a controltrack and an isolation track in accordance with the present invention;

FIG. 3 is a side perspective view cut at section B-B of an orifice plateincluding a control track and an isolation track in accordance with thepresent invention; and

FIG. 3 a is another side perspective view cut at section A-A of anorifice plate including a control track and an isolation track inaccordance with the present invention

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS

FIG. 1 shows an improved hydraulic mount assembly 10 according to thepresent invention. The mount assembly 10 is particularly adapted formounting an internal combustion engine and/or transmission to a frame ina motor vehicle. The mount assembly 10 includes a metal base plate 12and a molded body 14. The molded body 14 has an elastomeric portionmolded around a metal substrate, and includes a plurality of studs 16projecting outwardly to attach the molded body to the engine ortransmission. The base plate 12 is similarly equipped with a pluralityof outwardly projecting studs 17 to attach the base plate to the frame.

The base plate 12 and the molded body 14 are configured and joined toform a hollow cavity for receiving a damping liquid such as a glycolfluid. An elastomeric diaphragm 18 of natural or synthetic rubber isattached around its perimeter to the base plate 12 and/or to the body14, and extends across the cavity. The diaphragm 18 may include anannular rim section having a radially inwardly facing internal grooveformed between upper and lower shoulders such as is described in U.S.Pat. No. 5,263,693, the disclosure of which is hereby incorporated byreference. The shoulders are normally flexible so as to sealinglyreceive the periphery of a die-cast metal or plastic orifice plate 20.

The orifice plate 20 spans the cavity to define a primary chamber and asecondary chamber, as is well known. The orifice plate 20 includes afixed spiraling track 30, best seen in FIG. 2, and an isolation track 40that is generally within the same plane as the control track. Controltrack 30 has entrance 32 and exit 34 on either side of orifice plate 20.Track 30 may include varying degrees of traversing slope from entrance32 to exit 34 (e.g. gradual or aggressive). Isolation track 40 has anentrance 42 and an exit 44. In one embodiment, wall extension 46 blocksfluid from directly flowing from variable track entrance 42 to the exit44, promoting flow along the isolation track 40.

Referring now to FIG. 3, control track entrance 32 is shown on firstside 22 of orifice plate 20, with the control track exit 34 on a secondside 24 of fixed track 30. Isolation track 40 is formed by a rotatablemember 60 sealingly engaged and adjacent to a alignment plate 50 whichare both held against the orifice plate 20. Alignment plate 50 isdisposed about annular surface 26 and the first side 22 of orifice plate20, and adjacent to decoupler 70. Similarly, decoupler 70 is disposedabout the annular surface 26 of the orifice plate 20. The alignmentplate includes an exit 44, as seen in FIGS. 2 and 3, which exposesdecoupler 70 to fluid within the powertrain mount 10. Alignment plateexit 44 therefore engages decoupler 70 by exposing fluid to thedecoupler 70 at the end of isolation track 40. Rotatable member 60includes entrance 42 for fluid flow from the chamber formed from themolded body 14 and the orifice plate 20 (best shown in FIGS. 1 and 2).In another embodiment of the invention, wall 46 extends from lowersurface of rotatable member 60 into the variable track, preventingdirect fluid flow from entrance 42 to exit 44. In yet anotherembodiment, wall 46 extends from the alignment plate 50 similarlyblocking direct fluid flow from entrance 42 to exit 44, and forcing flowalong the length of the variable track 40, best seen in FIG. 3a. Wall 46extends from either the bottom side of the rotatable member 60 or thefrom the alignment plate 50 to force fluid flow through the entrance 42of the rotatable member 60, along the variable isolation track, andthrough the exit 44 to the exposed decoupler 70, blocking fluid fromdirectly flowing from the entrance 42 to the exit 44.

Referring back to FIG. 1, rotatable member 60 is held against orificeplate and in close proximity to alignment plate 50 by a containmentplate 80. An inside diameter 82 of the containment plate 80 is sized tobe closely received over legs 62 of the track member, while an outsidediameter 84 of the containment plate 80 is affixed to the orifice plate20. Thus, isolation track 40 may be generally structured by rotatablemember entrance 42 with track formed by alignment plate 50 and rotatablemember 60 and exit 44 exposing the decoupler 70.

In operation of one embodiment of the present invention, rotation of therotatable member 60 changes the length of the isolation track 40.Rotation may be performed with a motor assembly 90, which includes motor92 and encoder 94. The motor assembly 90 is operably connected to therotatable member 60 and is sealed off from the two tracks 30 and 40. Themotor assembly 90 is operably connected to a controller (not shown), andis sealed from operation of the isolation track. The encoder 94 orsimilar device measures an angular position of the rotatable member 60and communicates with the controller. The controller determinesvibration frequencies and rotates the motor to rotate the rotatablemember 60 changing the length of the variable track 40 and allowingfluid flow through the entrance of the rotatable member 42, along theisolation track, and to the decoupler 70 via the exit 44 of thealignment plate 50. A dynamic rate dip occurs as a function of resonatefrequency of the fluid in the track, which generally is a function oftrack length and area (i.e., freq˜Length/Area). The controller mayreceive one or more signals from a powertrain control module (notshown), such as r.p.m., to activate and rotate the motor and the trackmember entrance 42 to change the length of the isolation track 40,tracking engine disturbance frequencies and adjusts accordingly. Thus,the isolation track 40 operates to manage and control dynamic rate dipof engine operation, such as operational moments of force and othervibrations, to reduce the dynamic rate dip and reduce the stiffness ofthe mount 10 to further improve powertrain isolation.

Control track 30 performs as a passive track as it is fixed in length,continually operating to manage and control engine bounce or othervarious forms of road and environment input. Within the presentinvention, both the isolation track 40 and the control track 30 may beused simultaneously for wider range engine vibration disturbancefrequencies. For example, in one embodiment of the invention, isolationtrack resonance starts at engine disturbance frequencies of 20 Hz orhigher in the dual track orifice mount, allowing for higher endingresonance frequency. For large displacements across the mount, thedecoupler 70 within the isolation track 40 is maximized (i.e., bottomsout), and forces fluid to flow into the control track 30, which providesdamping to control the engine. Within the present invention, two orificetracks are provided; the control track 30 to provide damping and acontrollable isolation track 40 to provide a dynamic rate dip. As such,the present invention, includes, but is not limited to, the benefits ofincreasing the frequency range of the dynamic rate dip, and providing adynamic rate dip in driving as well as idle conditions.

While the embodiments of the invention disclosed herein are presentlyconsidered to be preferred, various changes and modifications can bemade without departing from the spirit and scope of the invention. Thescope of the invention is indicated in the appended claims, and allchanges that come within the meaning and range of equivalents areembraced therein.

1. A mount for vibration damning comprising: an orifice plate includinga fixed spiral track and an annular track formed therein, the fixedspiral track disposed about the orifice plate including an entrance on afirst side of the orifice plate and exit on a second side of the plate,and the annular track including an annular surface disposed about theorifice plate; a decoupler positioned adjacent the annular surface ofthe annular track; an alignment plate positioned adjacent the decouplerand the first side of the orifice plate, the alignment plate includingan exit adjacent the decoupler; and a rotatable member including anentrance formed therein, the rotatable member rotatably coupled to thealignment plate defining a variable track between the rotatable memberand the alignment plate, wherein a variable track length is determinedby rotation of the rotatable member.
 2. A mount comprising: an orificeplate including a fixed spiral track and an annular track formedtherein, the fixed spiral track disposed about the orifice plateincluding an entrance on a first side of the orifice plate and exit on asecond side of the plate, and the annular track including an annularsurface disposed about the orifice plate; a decoupler positionedadjacent the annular surface of the annular track; an alignment platepositioned adjacent the decoupler and the first side of the orificeplate, the alignment plate including an exit adjacent the decoupler;means for forming a variable track; and means for changing a variabletrack length and controlling fluid flow through the variable tracklength based on pre-determined vibration frequencies within thepowertrain mount.
 3. A hydraulic mount comprising: a base plateconnected to a molded member defining a cavity; an orifice plateconnected to one of the base plate or the molded member wherein theorifice plate spans the cavity defining a primary chamber and asecondary chamber, the orifice plate including a fixed track and anannular track formed therein, the fixed track spiralingly disposed aboutthe orifice plate having an entrance on a first side of the orificeplate and exit on a second side of the orifice plate, and the annulartrack having an annular surface disposed about the orifice plate; adecoupler disposed about the annular surface of the annular track; analignment plate sealingly formed about the decoupler and the first sideof the orifice plate, the alignment plate including an exit adjacent thedecoupler; a rotatable member rotatably coupled to the alignment plateand adjacent to the first side of the orifice plate, defining a variabletrack between the rotatable member and the alignment plate, therotatable member including an entrance formed therein; a containmentplate attached to the orifice plate retaining the rotatable memberagainst the orifice plate; and a motor engaged with the rotatable memberand adapted to rotate the rotatable member.
 4. A powertrain mountcomprising: an orifice plate including a fixed spiral track and anannular track formed therein, the fixed spiral track disposed about theorifice plate including an entrance on a first side of the orifice plateand exit on a second side of the plate, and the annular track includingan annular surface disposed about the orifice plate; a decouplerpositioned adjacent the annular surface of the annular track: analignment plate positioned adjacent the decoupler and the first side ofthe orifice plate, the alignment plate including an exit adjacent thedecoupler; a rotatable member including an entrance formed therein, therotatable member rotatable coupled to the alignment plate defining avariable track between the rotatable member and the alignment plate,wherein a variable track length is determined by rotation of therotatable member; and a containment plate attached to the orifice plate,the containment plate retaining the rotatable member against the orificeplate.
 5. A powertrain mount comprising: an orifice plate including afixed spiral track and an annular track formed therein, the fixed spiraltrack disposed about the orifice plate including an entrance on a firstside of the orifice plate and exit on a second side of the plate, andthe annular track including an annular surface disposed about theorifice plate; a decoupler positioned adjacent the annular surface ofthe annular track; an alignment plate positioned adjacent the decouplerand the first side of the orifice plate, the alignment plate includingan exit adjacent the decoupler; a rotatable member including an entranceformed therein, the rotatable member rotatably coupled to the alignmentplate defining a variable track between the rotatable member and thealignment plate, wherein a variable track length is determined byrotation of the rotatable member; and a motor assembly operably attachedto the rotatable member, the motor assembly including a motor and anencoder; and a controller operably coupled to the encoder; wherein theencoder measures an angular position of the rotatable member andcommunicates with the controller, and the controller determinesvibration frequencies and rotates the motor to rotate the rotatablemember allowing fluid flow through the rotatable member entrance, thevariable track, and the alignment plate opening.